The concept of Automatically Switched Optical Network (ASON) was proposed by International Telecommunication Union in March, 2000. The basic idea is as follows: a control plane is introduced to an optical transport network to realize allocation of network resources on demands and thus to realize the intelligent optical network, which can thereby make the optical transport network developed into a network accessible to any users and any places, and such network is composed of thousands of switching nodes and millions of terminals and is an intelligent automatically switched optical network.
Routing technology is one of core technologies of the ASON, and plays a crucial role in performing the dynamic routing of a connection. Topology total sets that can be selected by ASON routing include a set of connections between network element nodes (called external routing) and a set of optical fibre connections within a network element (called internal routing). The computing method of the internal routing can use an add-drop direction constraint algorithm, which selects a proper internal path from the set of the optical fibre connections within the network element. However, configurations for the set of the optical fibre connections within the network element need be manually set one by one for an ASON module on network management so as to generate the total set. Due to the above manual configuration, the prior art has the following problems.
(1) Error proneness. The internal optical fibre connections configured for the ASON are inconsistent with actual physical optical fibre connections.
(2) Much more effort. For example, for a simple five network element (NE) with 80 wavelength and full configuration, about one thousand internal optical fibre connections should be configured for the ASON.
(3) Inconvenient to transition from a soft Permanent Connection (SPC) service to a Switch Connection (SC) service. In the SPC service, configurations for the internal optical fibre connection are issued from the network management, and in the SC service, a connection setup request is initiated by a client and it is required to be independent of configurations from the network management.